1. Field of the Invention
The present invention relates to a photographic film cassette of the type that the leading section of a photographic film strip is advanced out of the cassette by rotation of a spool, and to a camera using such a photographic film cassette.
2. Description of Related Art
There is known a photographic film cassette having the structure wherein a photographic film strip (hereinafter simply called a film) is entirely housed within the cassette, and a film leading section (called a film leader) is advanced via a film passage mouth out of the cassette by rotation of a spool (e.g., refer to U.S. Pat. Nos. 4,834,306 and 4,832,275, and Japanese Patent Laid-open Publication No. 2-124564). This film cassette, different from a conventional film cassette having a film leader protruded beforehand out of a film passage mouth, has advantages in that the film loading operation using the film leader does not require a certain amount of skill and manual dexterity.
Such a film cassette is used for a camera having a cassette holder described, for example, in U.S. Pat. No. 4,841,319. The cassette holder is formed with a cassette receiving chamber into which a film cassette is inserted in the axial direction. The cassette holder is arranged to swing or pivot between an open position where the cassette holder is pulled out of the camera body, and a closed position where the cassette holder enters into the camera body. It is necessary for the construction of such a swingable cassette holder to lock the cassette holder at both the open and closed positions. In this context, the camera described in the above-cited U.S. Pat. No. '319 has a stopper mounted on the camera body, the stopper protruding within the rotation locus of the cassette holder to stop the cassette holder at the open position.
Generally speaking, an exposed film is completely rewound on the cassette after taking photographs. Therefore, for the above-described film cassettes, it is impossible to visually discriminate between unused (unexposed) film cassettes and used (exposed) film cassettes. There arises therefore a risk of reloading an exposed film cassette into a camera.
The above-described camera has a stopper for stopping the cassette holder at the open position, the stopper being formed integrally with the camera body. Therefore, the stopper is likely to hinder the operation of mounting the cassette holder on the camera body, posing a problem of mounting operability. Furthermore, a mechanism for holding the cassette holder at the open position and a mechanism for locking it at the closed position are separately provided, thereby increasing the number of components.